The invention concerns a false-twist-textured filament yarn of synthetic polymers, comprising a filament group forming the core and a filament group on the outside of the core and partially wrapped around the core, wherein the two filament groups are produced from the same or different polymers. Further, the invention concerns a procedure for manufacturing the above mentioned filament yarn.
In the last several years, the interest in synthetic filament yarns resembling natural fiber yarns has been steadily increasing. The closer the similarity with natural fiber yarns, the better the so-called "spun-like effect". In the last few years, core-wrapping threads have gained greater importance, since a relatively good spun-like effect can be obtained with such threads. For example, German patent applications Nos. DE-OS 19 15 821 and 22 55 460 concern a procedure for manufacturing synthetic continuous core yarns of false-twist-texture, which consist of at least one core component and one sheath component, whereby both polyamide and polyester have been used.
According to this procedure, core yarns with good spunlike effect can be manufactured, but when these core yarns are to be processed, for example on a knitting machine, great problems occur due to frequent machine shut-offs. The presence of small fibrils extending from the sheath thread causes great back-holding-force in the knitting, which must be overcome in order to continue the knitting procedure. Since great back-holding-force leads to deficiencies in the produced knitted goods, shut-off devices are applied to the knitting machines which shut off the machine when the back-holding-force becomes too great. A large number of shutdowns, as will occur with these core yarns, is not economical for the processor.
On the other hand, German utility model DE-GM No. 77 34 062 describes a voluminous false-twist-textured polyester filament yarn, consisting of a core with between 12 and 100 fibrils and a sheath with between 1 and 10 fibrils, wherein the fibrils of the core group have a lesser denier than the fibrils of the sheath group. The yarn according to the abovementioned utility model has a crepe-like effect, not a spunlike effect; on the other hand, it runs quite well on the machine, i.e. there is little back-holding-force in the knitting, which causes almost no shut-downs during the knitting.
The purpose of the present invention is to make available a filament yarn with false-twist-texture, comprising a filament group forming the core and a filament group wrapped around the core, whereby the abovementioned disadvantages can be avoided. It concerns the production of a filament yarn which has a good spun-like effect and runs well during the processing, for example in knitting machines.